#container {
  display: flex;
  justify-content: center;
  /* position: relative; */
  > div {
    display: block;
  }
}

header {
  /* display: flex; */
  /* justify-content: center; */
}

div.month {
  display: grid;
  /* grid-auto-flow: column; */
  /* gap: 1em; */
  grid-template-columns: repeat(7, 1fr); /* 3列に指定 */
  width: 90vw;
  margin: auto;
  margin-bottom: 1em;
  margin-top: -1em;

  div {
    border: 1px solid;

    &.day {
      aspect-ratio: 1;
      display: flex;
      justify-content: flex-end;

      &.spliter {
        border-top: 2px solid;
        height: calc(auto - 1px);
      }
    }
  }
}